I had 17GB of free before triggering Big Sur update from System Prefrences > Software Update > Upgrade Now. Midway through that process I shut the lid of my MacBook the update to fail. It says something likeL: “Update failed due to network issues.”

Which makes sense, since the network does not stay connected when put to sleep.

The problem is when I check my MacBook now, only 5GB remains free. This 5GB of free space remains the same even after multiple restarts.

I doubt re-downloading is wise; the download GUI indicates that the download starts from scratch. I have hence not tried this.

However, before starting the update for the first time around it would refuse unless at least 15.95GB was free, and now it shows no such warning.

It is most likely that the update stored as temporary file(s) while downloading. But if so, restarting should clear out the temporary files since — as I understand it — a shutdown/restart involves deletion of temp files, yes?

Seeing as there is no change in the amount of free space after restarts, what can I do next?

Is there any command to purge these update files?

2 Answers 2


Just continue the Big Sur download and run the update.

That 12GB of space should be a partial download of Big Sur.

In my experience, Apple macOS updates are cumulative in downloads. Meaning when you closed the lid on your MacBook all that happened is the download was suspended. It will not start from square one again. It will simply continue the download where it left off. And since the Big Sur update package is around 15GB, you now have 12GB downloaded so all you need to do is wait for the remaining 3GB to download and you should be good.

And yes, macOS and many other OSes — not just Unix and Linux systems — clear cached data and such on reboots. But in the case of this macOS update it is not considered removable cached data for the reason I explained above. If everyone in the world had to start a 15GB download from square one each time there was a network issue, nobody would get an update and Apple’s servers would have to serve more that 15GB for each download attempt. Bad user experience and bad for Apple’s bandwidth management.

That said, if you are truly concerned about free space and do want to start from square one, download Onyx and run it to clear your filesystem caches. While some people say Onyx causes problems, never in my years of using it have I had issues. Download it, run it and you should be good.

And if a re-download fails — or Onyx doesn’t work — just look in your main system’s Applications folder — which should be located at /Applications/ in the Terminal — and look for the “Install macOS Big Sur” application and just trash it. The data is either in the deeper system cache or it is there right in the Applications folder as an application like all other applications.


Search for macOS Big Sur.appdownload and trash it.


  1. Command + space
  2. Search `macOS Big Sur.appdownload" but don't hit Return
  3. In the search result preview, select “Show all in Finder,” which takes you to the location of the download file.
  4. Trash this file

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .